sedimentary

Bituminous Coal

Organic-rich sedimentary rock (Complex hydrocarbons)

AI-generated identification · may be incorrect

Hardness: 0.5–2.5 (Mohs scale); Color: Black to dark brown; Luster: Sub-metallic to dull; Crystal structure: Amorphous (non-crystalline); Cleavage: Rectangular blocky fracturing (cleat); Specific gravity: 1.1–1.5

Hardness: 0
Color: Black to dark brown
Luster: Sub-metallic to dull

Identified March 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deep burial and lithification of peat over millions of years (diagenesis). Most deposits date to the Carboniferous or Cretaceous periods (360–66 million years ago) in swampy, coastal environments.

Uses & applications

Primarily used for electricity generation (thermal coal) and steel production (coking coal). It is also used as a raw material for synthetic fuels and various chemical industries.

Geological facts

It is the most abundant form of coal in the United States. Unlike the softer 'lignite', bituminous coal contains a high carbon content and produces more heat, though it also contains sulfur which can contribute to acid rain when burned.

Field identification & locations

Identify in the field by its blocky fracturing (cleat), dark black color, and the fact that it will leave a black streak on a porcelain plate and feels relatively light for its size. It is commonly found in basins like the Appalachian Basin or the Illinois Basin.